In monolithic integrated circuit construction, suitable composite transistors have been constructed to enhance performance of NPN transistors. One such composite transistor is taught in U.S. Pat. No. 4,236,119 to Carl R. Battjes, wherein a three-terminal composite NPN transistor comprises three NPN transistors exhibiting current gain and frequency response characteristics that approximately double the performance of a single NPN transistor.
In U.S. Pat. No. 4,371,792 to Robert C. Dobkin, a three-terminal composite NPN transistor employing two NPN and two PNP transistors exhibits characteristics that are superior to those of a conventional single NPN transistor.
In electronic circuit design, the circuit constraints and biasing voltage available often warrant the use of PNP transistors. However, because of generally poor performance of PNP transistors, notably typically very low beta and poor linearity, circuit designers attempt to find solutions in which NPN transistors predominate.